Belaying – The act of regulating the amount of slack in a rope between you and your climbing partner. When they are leading you generally want to be feeding out the rope, and when top roping you want to be taking it in. You are also responsible for controlling the rope, and counter balancing the force if your partner was to take a fall.
Cam – A mechanical device that is used as fall protection when lead climbing, and for anchor point set up. It has moving parts and is very effective in horizontal or vertical cracks.
Crag – The geographical rock feature on which you climb!
Friend – See cam (and never was there a truer nickname, they tend to fit in cracks where nothing else will)
Gear – The devices used as fall protection, anchor establishment and belaying by climbers.
Harness – The device that attaches you to your climbing rope, often attaching at the waist and legs.
Helmet – A safety device that will offer protection of your head in the event of a fall and if something was to land on it.
Hex – Hollow vaguely hexagonal bits of gear used similarly to nuts, they will tend to fit in wide more awkward shaped cracks, and if well placed will be stronger.
Leader – The climber who makes the initial assent of a route, placing gear as fall protection as they go. Who then establishes secure anchor points from which they can they belay their partner (second).
Leading – The act, as above, performed.
Karabiner – There are several different types available, all with slightly different purposes. There are generally oval in shape, made from metal and are very strong. They all have a gate which is spring loaded so that it shuts automatically. The type of most interest when belaying is called a screw-gate, because the gate has a screw system that once locked, prevents the gate opening by accident. The type of interest when leading and seconding is the snap gates; they snap shut automatically but have no screw system.
Nuts – Effectively a wedge that can be placed in some cracks, which is used as fall protection and anchor point creation.
Nut-key – Tool used by second to help extract bits of gear from the rock.
Quickdraw – Is constructed of a small sling and two snap gate karabiners, of which one attaches to the gear placed in the rock face, and one through which the rope is threaded.
Runners – The placements in the rock face, through which the rope is threaded, used by leaders to protect them in the event of a fall.
Rack – A collection of gear.
Rope Drag – Created by the friction of rope running through the runners at too steep an angle. It is also caused by incorrect length of runner placement (the rope is not in a direct line from leader to second), and any problems of rubbing against the rock that this may cause.
Second – The climber that climbs up after the leader and retrieves the gear (fall protection) that was placed by them. They are secured from the top by the rope.
Wires – See nuts